A variety of applications exist for installing threaded screw anchors or squash nuts in sheet metal panels, walls, and other surfaces for a variety of purposes. Generally, such threaded screw anchors or squash nuts are installed from the outer surface only and include collapsable legs extending through a hole in the panel or wall surface to a preestablished distance on the blind or opposite side. These legs terminate in a threaded end portion; so that when a screw is inserted into the squash nut and turned, the action of the screw working against the head pressing on the outer flange of the squash nut causes the collapsable legs to collapse outwardly and grip the panel on the reverse side. Normally, such squash nuts are installed by hand using a manually operated screw driver or, in some cases, a power-driven screw driver. A relatively large number of turns of the screw, which is inserted into the squash nut, however, is necessary to collapse the squash nut onto the reverse side of the panel in which it is installed. Then it is necessary to reverse the screw by the same number of turns to remove it. Consequently, even if a power-driven screw driver is used, the time required for the installation of the squash nut is relatively long. If the squash nut is collapsed manually, the length of time for this operation is even greater.
In an effort to facilitate the installation of threaded screw anchors or squash nuts in a more rapid fashion than is possible with the insertion, turning and subsequent removal of a screw of the type normally associated with such squash nuts, various types of hand-tools have been developed in the past. These tools generally resemble tools of the type used for installing tubular rivets of the collapsable type in various surfaces. A typical tool is disclosed in the Croessant U.S. Pat. No. 3,031,098, issued Apr. 24, 1962. This patent discloses a tool used to install blind screw anchors in which a detachable pull rod extends through the tool body. One end of the rod has a knurled knob attached to it and the other end is threaded for engagement with the threaded portion of a threaded screw anchor. A spring is provided inside the tool and the knob is turned several turns to wind-up the spring, placing it under tension. A threaded screw anchor then is threaded onto the threaded end of the pull rod, and the anchor installed on the tool then is pushed into a hole in the plate or other surface in which the anchor is to be mounted. A pliers-type of action is provided for drawing the pull rod into the tool relative to the end of the tool pressing against the outer flange of the squash nut to collapse the squash nut and clamp it onto the plate into which it has been inserted. Release of the handles then releases the spring to unwind or unthread the pull rod; so that the operation can be repeated. This tool is a relatively cumbersome tool to use because of the necessity for the winding-up the spring and the number of different steps which must be undertaken in order to use the tool.
Another tool which has been developed for setting threaded bushes also uses a pliers-type of squeeze handle operation for inserting and collapsing threaded bushes by using a pull rod type of action. This tool is disclosed in the U.S. Pat. to Fluester, No. 4,147,047, issued Apr. 3, 1979. The mandrel or pull rod is fixed to a mandrel puller within the tool which is rotatably and slidably mounted in a body portion of the tool. When the tool is operated, the mandrel puller is pulled into the tool; so that the threaded bush strikes the body portion, is held and then is expanded upon further movement of the mandrel puller. The threaded bush is released by rotating the mandrel puller relative to the body portion by rotating a knurled knob on the opposite end of the mandrel puller which extends through the operating head portion of the tool. The nature of this arrangement is one which is cumbersome and relatively difficult to use. The tool does constitute an improvement over the use of a screw and screw driver to collapse the threaded bush, however.
Several other patents for rivet tools employ similar constructions to the devices described above in conjunction with the Croessant and Fluester patents. These additional patents, however, all are subject ot disadvantages in operation of the nature of the disadvantages discussed above in conjunction with Croessant and Fluester. Such rivet tools are disclosed in the U.S. Pats. to Underland No. 3,933,019, issued Jan. 20, 1976; Waner No. 2,069,907 issued Feb. 9, 1937; Warner, No. 2,188,422, issued Jan. 30, 1940; and Caddin, No. 2,283,665, issued May 19, 1942.
It is desirable to provide an adapter which can be used in conjunction with a conventional squeeze-type rivet installation tool to modify such a gun for the purpose of enabling it to apply and attach threaded bushes or squash nuts in plate metal surfaces, and the like. It is further desirable that such an adapter should be simple to construct and simple to operate; so that rapid installation of squash nuts by the use of a hand-operated rivet installation tool employing the adapter is possible.